Centrifugal clutch

ABSTRACT

D R A W I N G THE DISCLOSURE IS DIRECTED TO A VARIABLE RATIO CENTRIFUGAL CLUTCH HAVING DRIVING AND DRIVEN ASSEMBLIES CONNECTED BY AN ENDLESS BELT. THE DRIVING ASSEMBLY CONSISTS OF A PAIR OF SHEAVES AFFIXED TO A DRIVE SHAFT, ONE BEING AXIALLY STATIONARY AND THE OTHER BEING AXIALL MOVABLE WITH RESPECT THERETO. THE MOVABLE SHEAVE FORMS PART OF A CLOSED HOUSING WHICH FULLY ENCLOSES A PLURALITY OF FLYWEIGHTS PIVOTALLY MOUNTED ON THE SHAFT FOR ROTATION THEREWITY. IN RESPONSE TO INCREASES IN DRIVE SHAFT SPEED, THE FLYWEIGHTS SWING OUTWARD AND ENGAGE THE HOUSING, MOVING IT IN ITS ENTIRETY ALONG THE SHAFT TO BRING THE SHEAVE TOGETHER.   D R A W I N G

Jan. 1, 1914 E w, UN R6. 27,858

CENTRIFUGAL CLUTCH Original Filed Oct. 24, 1969 2 Sheets-Sheet 1 FIG. 1V

M7 77 6/ 56 0 1 4 7; 75 1 65 14- 65 72. 7 7479 76 .5 r 56 I 75 75 63 Zf2, 63 EUGENE v ii ggr-luu .AT TORNE YS Jan. 1, 1974 E. w. LAUGHLIN Re.27,858

CENTRIFUGAL CLUTCH Original Filed 001;. 24, 1969 2 Sheets-Sheet 3INVENTOR.

EUGENE WLAUGHLIN A T TORNEYS United States Patent 27,858 CENTRIFUGALCLUTCH Eugene W. Laughlin, Minneapolis, Minn., by Textron, Inc.,assignee, Providence, RI.

Original No. 3,605,510, dated Sept. 20, 1971, Ser. No. 869,165, Oct. 24,1969. Application for reissue Sept. 20, 1972, Ser. No. 290,631

Int. Cl. F16h 55/52 US. Cl. 74230.17 E 16 Claims Matter enclosed inheavy brackets fl appears in the original patent but forms no part ofthis reissue specification; matter printed in italics indicates theadditions made by reissue.

ABSTRACT OF THE DISCLOSURE The disclosure is directed to a variableratio centrifugal clutch having driving and driven assemblies connectedby an endless belt. The driving assembly consists of a pair of sheavesaffixed to a drive shaft, one being axially stationary and the otherbeing axially movable with respect thereto. The movable sheave formspart of a closed housing which fully encloses a plurality of flyweightspivotally mounted on the shaft for rotation therewith. In response toincreases in drive shaft speed, the flyweights swing outward and engagethe housing, moving it in its entirety along the shaft to bring thesheaves together.

The invention falls within the art of centrifugal clutches generally,and is specifically directed to centrifugal clutches consisting ofdriving and driven assemblies that vary the ratio of input shaftrotation to output shaft rotational.

Centrifugal clutches of this specific type find particular applicationin conjunction with smaller internal combustion engines where the use ofgear transmission is impractical or too clostly. By providing a variableratio of input to output rotational speed, the clutch serves as bothclutch and transmission.

The driving assembly of a variable ratio centrifugal clutch ordinarilyconsists of a pair of sheaves mounted for rotation on a drive shaft, oneof the sheaves being axially stationary on the shaft and the other beingaxially movable to effect the clutch operation. The position of themovable sheave is governed by a plurality of flyweights that rotate withthe shaft and are mounted to swing radially outward in response toincrease in shaft speed. The flyweights include cam surfaces, andthrough engagement with cooperating cam follower surfaces the sheave ismoved axially along the shaft.

Since proper operation of the clutch is dependent on movement of theflyweights, it is imperative that all of the moving parts, includingflyweights, pivotal connections, cam and cam following surfaces, be keptclean and protected from dirt, mud and other potentially damagingsubstances.

An obvious solution to the problem is to enclose the moving parts in ahousing that revolves with the drive shaft. However, this raises thefurther problem of axial movement of the enclosure and maintaining theprotection of moving parts throughout the range of axial movement of themovable sheave. Existing clutch assemblies solve this problem throughthe use of a telescoping housing, part of which remains stationary andpart of which moves with the movable sheave. This is not a completelysatisfactory solution since the telescoping surfaces are capable ofcarrying dirt into the housing, particularly where the telescopingsurfaces separate at the furthest axial position of the movable sheave.The resulting gap is also extremely unsafe since it allows the escape ofbroken or loosened parts from the enclosure.

Re. 27,858 Reissued Jan. 1, 1974 Another disadvantage of telescopingenclosures is the inherent lack of connecting support between theenclosure sections. The telescoping extension of the movable section isgenerally unsupported thereby placing a good deal of strain on thesliding bearing. Consequently, misalignment of this section is morelikely, not to mention the difiiculty in affixing the section to theshaft for balanced rotation therewith.

My invention is believed to solve these problems through the provisionof an enclosed housing part of which forms the movable sheave, and whichis entirely movable on the shaft. Within the enclosure is disposed anaxially stationary frame that rotates with the shaft and pivotallycarries the flyweights. For increases in shaft speed the flyweightsengage the housing to effect axial movement with respect to thestationary sheave and thereby perform the desired clutching function.

The inventive clutch assembly offers full protection from dirt at alltimes, fully encloses the moving parts at all times and is structurallysound throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of avariable ratio centrifugal clutch consisting of a driving portion and adriven portion;

FIG. 2 is a top elevational view of the variable ratio centrifugalclutch, portions thereof broken away;

FIG. 3 is an enlarged cross-sectional view of the centrifugal clutchdriving portion taken along the line 33 of FIG. 2;

FIG. 4 is the same as FIG. 3 with parts thereof removed;

FIG. 5 is an enlarged sectional view of the clutch driving portion inone operating position, taken along line 55 of FIG. 1;

FIG. 6 is a view of FIG. 5 taken in another operating position, portionsthereof broken away; and

FIG. 7 is a fragmentary sectional view of a roller retaining member,taken along the line 7--7 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a variable ratiocentrifugal clutch is shown, consisting of a driving assembly 11 and adriven assembly 12 interconnected by an endless belt 13. Referringadditionally to FIG. 2, driving assembly 11 is shown to be mounted on anoutput drive shaft 14 of a power plant (not shown), while drivenassembly 12 is mounted on an output shaft 15 adapted for connection witha utilization device (not shown). Driven assembly 12 consists of astationary sheave 16 and a sheave 17 that is axially movable on shaft 15as discussed below.

Forming part of sheave 17 are three ramp sections 19 (only two of whichcan be seen in FIG. 2) and a hub 21. A ramp member 22 includes threeramp surfaces 23 corresponding to ramp sections 19, and a centralportion 24 which is suitably secured to shaft 15 such as by aslotand-key or splining. A spring 28 is disposed in compression betweensheave 17 and member 22, and the entire assembly is held in place bybolt 26 which threads into shaft 15. Hub 21 has a plurality of spacers27 which keep spring 28 in proper alignment.

As assembled, sheave 17 is normally urged toward stationary sheave 16 byspring 28, but by application of a proper force spring 28 can beovercome so that sheave 17 moves both rotationally and axially by virtueof ramp sections 19 engaging ramp surfaces 23. In order to preventexcess wear therebetween, ramp surfaces 23 are provided with pads 29which also provide a desired frictional relation between the two.

Driving assembly 11 also has a stationary sheave 31 fixed on shaft 14and a movable sheave 32 (see also FIG. 4) that forms part of a movablehousing 33. Housing 33 is normally urged away from sheave 31, but inresponse to an increasing angular velocity of shaft 14 moves axiallyforward as shown by the dotted lines in FIG. 2. Belt 13 normallyoccupies a slack position against shaft 14 when driving assembly 11revolves slowly, but as housing 33 progresses axially it is forcedradially outward, also as represented by dotted lines.

With the movements of belt 13 radially outward on driving assembly 11,movable sheave 17 of driven assembly 12 also begins to move away fromsheave 16 against the bias of spring 28. However, before this can occurthe coefficient of static friction existing between pads 29 and rampsections 19 must be overcome. Rotation of both assemblies 11 and 12 isin the counterclockwise direction as seen in FIG. 1, so that when thestatic friction of pads 29 and the biasing force of spring 28 areovercome sheave 17 moves clockwise against belt movement, and thegripping force between belt 13 and sheaves 16 and 17 therefore remainsgreat. Thus, for increasing angular velocity of shaft 14, housing 33approaches stationary sheave 31 to move belt 13 radially outward fromits slack position, which in turn causes belt 13 to move radially inwardwith respect to driving assembly 12, resulting in rotational movement ofoutput shaft 15.

Since the radial position of belt 13 with respect to sheaves 31 and 32of driving assembly 11 and sheaves 16, 17 of driven assembly 12 variesas a function of the angular velocity of shaft 14, it follows that theratio of revolutions of the shaft 14 to revolutions of the shaft alsovaries as a function of shaft 14 speed. At low r.p.m.s, this ratio isinfinite since shaft 14 revolves but belt 13, in its slack position, isunable to transmit rotational energy to driven assembly 12, and ouputshaft 15 cannot revolve. With increasing r.p.m.s by shaft 14, this ratiois decreased since the radial distance of belt 13 from shaft 14 isincreasing while its distance from that of shaft 15 is decreasing. Byvirtue of its variable ratio feature, the centrifugal clutch performsthe function of both clutch and transmission.

Referring to FIG. 5, which shows driving assembly 11 in detail, it canbe seen that shaft 14 has a tapered end which receives an elongatedsleeve 41. Sleeve 41 is affixed to shaft 14, by means of a slot 42 and akey 43, so that both members rotate together. Fixed sheave 31 is splinedon sleeve 41 for rotation therewith.

A spider 44 consisting of a hub 45 and three radially extending arms 46(see also FIG. 3) is splined on sleeve 41 for rotation therewith, andalso abuts a stepped portion 47 of sleeve 41 to prevent axial movementto the righ. Each of the arms 46 has an alignment hole 50 the purpose ofwhich is described below. A keeper 48 slides over sleeve 41 and abutsthe opposite side of hub 45 to prevent axial movement of spider 44 tothe left. In the preferred embodiment, housing 33 is bell-shaped withthe open end facing sheave 32. To strengthen housing 33 and to resiststresses at its outer end, a plurality of triangular webs 77 aredisposed on the inner surface of housing 33 between the open end andcenter of the housing.

Sheave 32 has a flange portion of slightly greater diameter than theopen end of housing 33 and thereby receives the end in overlappingrelation. To prevent relative rotation between sheave 32 and housing 33,a plurality of shoulder portions 75 are formed on the inner face of theflange portion of sheave 32 (FIGS. 4-5). Corresponding recesses 76 areformed in housing 33 that laterally abut shoulder portions 75 whensheave 32 and housing 33 are brought together. Movable sheave 32includes a bearing surface 52 which rides on sleeve 41 and forms a sealtherewith. For the same purpose, housing 33 is provided with a collar 53forming a bearing surface. This structural arrangement enables sheave 32and housing 33 to completely enclose spider 44, thus preventing exposureto damaging substances. Studs 49 passing through holes 50 permit analigned, axial movement of sheaves 32 and housing 33 on sleeve 41, andsimultaneousl carry these enclosure members in rotational movement.

The resulting enclosure for spider 44, as formed by movable sheave 32,housing 33 and studs 49, is extremely strong by virtue of itsconstruction, and yet permits fully aligned and balanced operation.

The entire assembly is held in place by a cap 54 which is threaded intosleeve 41 to abut keeper 48. A central bolt 55 screws into a threadedportion of shaft 14 to bring shaft 14 and sleeve 41 into tightfrictional engagement.

The movable portion of driving assembly 11, which consists of movablesheave 32, movable housing 33 and collar 53, is normally biased to theleft (with respect to FIG. 5) against cap 54 by a spring 56 mounted incompression between hub 45 of spider 44 and collar 53.

Pivotally connected to each of the arms 46 of spider 44 is a flyweight61 having a predetermined shape and mass. The leading edge of eachtlyweight 61 forms a cam surface 62 that engages a low friction roller63 carried by movable sheave 32. Roller 63 is carried by an axle 64,which, as shown in FIG. 7 is inserted into a recess 65 and held in placeby a retainer clip 66 on each end.

With shaft 14 at rest, fiyweights 61 occupy the position as shown inFIG. 5. As shaft 14 begins to rotate and for increasing rotational speedthereof, fiyweights 61 swing upwardly and outwardly, moving the entireenclosure (sheave 32, housing 33 and studs 49) axially to the right byvirtue of the engagement between cam surfaces 62 and rollers 63 and theresulting axial force created thereby. Since the entire enclosure moveswith respect to spider 44 and flyweight 61, there is no telescoping orseparation of enclosure sections, and protection is therefore maintainedthrough the full range of operation.

What is claimed is:

[1. A centrifugal clutch comprising:

(a) rotatable shaft means;

(b) first rotatable means mounted on the shaft means and axiallystationary thereon, the first rotatable means having a first clutchingsurface;

(c) second rotatable means mounted on the shaft means and comprising (i)a rotatable enclosure mounted on the shaft means and axially movablethereon, the rotatable enclosure forming a second clutching surfaceoperating in association with the first clutching surface;

(ii) third rotatable means mounted on the shaft means and axiallystationary thereon, the third rotatable means disposed within theenclosure;

(iii) and a plurality of fiyweights pivotally mounted on one of saidrotatable enclosure and said third rotatable means and arranged to moveradially outward with increasing rotational velocity of the shaft means,the fiyweights engageable with the other of said rotatable enclosure andsaid third rotatable means to effect said axial movement of therotatable enclosure with respect to the first rotatable means] [2. Thecentrifugal clutch as defined in claim 1 wherein:

(a) the first rotatable means comprises a first sheave;

(b) and the rotatable enclosure comprises (i) a second sheave operatingin association with the first sheave and axially movable on the shaftmeans;

(ii) an axially movable housing having an open end, the second sheaveengageable with the housing to close the open end;

(iii) and means for holding the second sheave and the housing in tightengagement] [3. The centrifugal clutch as defined by claim 1, whereinthe fiyweights are mounted on the third rotatable means] [4. Thecentrifugal clutch as defined by claim 3, wherein the third rotatablemember comprises a hub with a plurality of arms extending radiallyoutward therefrom, and a flyweight is mounted on each of the arms.]

[5. The centrifugal clutch as defined by claim 3, wherein a low frictionroller for each fiyweight is mounted on the inner side of the rotatableenclosure for rolling engagement therewith] [6. The centrifugal clutchas defined by claim 2, wherein:

(a) the periphery of the second sheave forms a flange portion extendingtoward the housing and having a predetermined diameter;

(b) and the housing is bell-shaped, the open end having a diameter lessthan that of the flange portion and insertable therein in overlappingrelation] [7. The centrifugal clutch as defined by claim 1, where- (a) aplurality of openings are formed in the third rotatable means;

(b) and further comprising (i) a plurality of said members connectingopposite sides of the enclosure and disposed essentially parallel to therotatable shaft means;

(ii) each of the stud members disposed in one of the openings andslidable movable therethrough] [8. The centrifugal clutch as defined byclaim 1, and further comprising spring means disposed between saidrotatable enclosure and said third rotatable means and arranged tonormally bias the rotatable enclosure away from the first rotatablemeans] [9. The centrifugal clutch as defined by claim 8, wherein thespring means comprises a coil spring encircling the shaft means anddisposed in compression] [10. The centrifugal clutch as defined by claim1, wherein the rotatable enclosure slidably engages the shaft means, andfurther comprises bearing means for facilitating said slidableengagement] [11. The centrifugal clutch as defined by claim 6, whereinthe bell-shaped housing further includes a plurality of strengtheningwebs disposed on the inner side of the housing and extending from apoint near the open end toward the center of the housing] [12. Thecentrifugal clutch as defined by claim 6, wherein (a) the second sheavefurther includes shoulder portions disposed on the inner face of theflange portion;

(b) and the insertablc end of the bell-shaped housing is constructed toreceive and laterally abut the shoulder portions] [13. The centrifugalclutch as defined by claim 6,

wherein:

(a) a plurality of openings are formed in the housing corresponding withthe openings in the third rotatable means;

(b) and the means for holding the second sheave and housing comprises(i) a plurality of studs affixed to the second sheave, each of the studsslidably extending through one of the openings in the third rotatablemeans and a corresponding one of the openings in the housing;

(ii) and fastening means on each of the studs for tightening the housingagainst the second sheave] [14. A centrifugal clutch comprising:

rotatable shaft means;

first rotatable means mounted on the shaft means and axially stationarythereon, the first rotatable means havinfig a first clutching surface;

second rotatable means mounted on the shaft means and comprising arotatable enclosure mounted on the shaft means axially movable thereon,the rotatable enclosure forming a second clutching surface operating inassociation with the first clutching surface;

third rotatable means mounted on the shaft means within said rotatableenclosure; and

a plurality of flyweights pivotally mounted on one of said rotatableenclosure and said third rotatable means and arranged to move radiallyoutward with increasing rotation velocity of the shaft means, theflyweights engagement with the other of said rotatable enclosure andsaid third rotatable means to effect said axial movement of of rotatableenclosure with respect to the first rotatable means] [15. A centrifugalclutch comprising:

rotatable shaft means;

first rotatable means mounted on the shaft means and axially stationarythereon, the first rotatable means having a first clutching surface;

second rotatable means mounted on the shaft means and comprising arotatable enclosure mounted on the shaft means and axially movablethereon, the rotatable enclosure forming a second clutching surfaceoperating in association with the first clutching surface; and

actuating means within said rotatable enclosure for effecting axialmovement thereof with respect to the first rotatable means, saidactuating means including a plurality of flyweights and means foroperatively mounting said flyweights within the rotatable enclosure, theflyweights constructed and arranged to move radially outward withincreasing rotational velocity of the shaft means and to exert aresulting axial force on the rotatable enclosure to effect said axialmovement] [16. A centrifugal clutch comprising:

rotatable shaft means;

a rotatable enclosure mounted on the shaft means and axially movablethereon, said rotatable enclosure carrying a first clutching surface;

first rotatable means mounted on the shaft means and axially stationarythereon, the first rotatable means disposed within the rotatableenclosure;

a plurality of flyweights mounted on one of said rotatable enclosure andsaid first rotatable means and arranged to move radially outward withincreasing rotational velocity of the shaft means, the flyweights beingengageable with the other of said rotatable enclosure and firstrotatable means to effect axial movement of the rotatable enclosure onthe shaft means; and

second rotatable menas including a second clutching surface foroperating in clutching relationship with the first clutching surface andfor providing an output for the centrifugal clutch which varies as afunction of rotational velocity of the shaft means] 17. A centrifugalclutch, comprising:

(a) rotatable shaft means;

(b) first rotatable means mounted on the shaft means for rotationtherewith and axially stationary thereon, the first rotatable meanshaving a first clutching surface;

(c) second rotatable means mounted on the shaft means for rotationtherewith and defining a second clutching surface operable inassociation with the first clutching surface, the second rotatable meansincluding a bearing support portion engageable with the rotatable shaftmeans to permit axial movement rlzere over;

(d) third rotatable means mounted on the shaft means for rotationtherewith and including a bearing support portion engageable with therotatable shaft means to permit axial movement thereover;

(e) said second and third rotatable means being constructed and arrangedto cooperobly merge and define a rigid rotatable enclosure with thebearing support portions axially spaced to provide distributed bearingsupport for the rigid enclosure as it moves axially over the rotatableshaft means;

(f) a plurality of structural support means interconnecting opposedsides of the second and third rotatable means, said structural supportmeans being equiangularly spaced between the rotatable shaft means andthe extreme periphery of the rotatable enclosure;

(g) fourth rotatable means mounted on the shaft means for rotationtherewith and axially stationary thereon, the fourth rotatable meansbeing disposed within the rotatable enclosure;

(h) a plurality of flyweights pivotally mounted on one of the rotatableenclosure and the fourth rotatable means and arranged to move radiallyoutward with increasing rotational velocity of the shaft means, each ofsaid flyweights being engageable with the other of said rotatableenclosure and the fourth rotatable means to effect axial movement of therotatable enclosure toward the first rotatable means;

(i) and coil spring means encircling the rotatable shaft means anddisposed to normally urge the rotatable enclosure away from the firstrotatable means.

18. The centrifugal clutch defined by claim 17, wherein at least aportion of each of said structural support means threadably engages oneof the second and third rotatable means.

19. The centrifugal clutch defined by claim 17, wherein each of saidstructural support means movably engages the fourth rotatable means inguided relation therewtih.

20. The centrifugal clutch defined by claim 19, whereing said structuralsupport means comprise elongated stud members extending throughappropriately disposed openings in said fourth rotatable means.

21. The centrifugal clutch defined by claim 17, wherein the coil springmeans is compressibly disposed between the rotatable enclosure andfourth rotatable means.

22. The centrifugal clutch defined by claim 17, wherein the first andsecond clutching surfaces comprise sheaves.

23. A centrifugal clutch, comprising:

(a) rotatable shaft means;

(b) first rotatable means mounted on the shaft means for rotationtherewith and axially stationary thereon, the first rotatable meanshaving a first clutching surface;

(c) second rotatable means mounted on the shaft means for rotationtherewith and defining a second clutching surface operable inassociation with the first clutching surface, the second rotatable meansincluding a bearing support portion engageable with the rotatable shaftmeans to permit axial movement thereover.

(d) third rotatable means mounted on the shaft means for rotationtherewith and including a bearing support portion engageable with therotatable shaft means for rotation therewith and including a bearingsupport portion engageable with the rotatable shaft means to permitaxial movement thereover;

(e) said second and third rotatable means being constructed and arrangedto cooperably merge and define a rigid rotatable enclosure with thebearing support portions axially spaced to provide distributed bearingsupport for the rigid enclosure as it moves axially over the rotatableshaft means;

(f) fourth rotatable means mounted on the shaft means for rotationtherewith and axially stationary thereon, the fourth rotatable meansbeing disposed within the rotatable enclosure;

(g) a plurality of fiyweights pivotaily mounted on one of the rotatableenclosure and the fourth rotatable means and arranged to move radiallyoutward with increasing rotational velocity of the shaft means, each ofsaid flyweights having a cam surface engageable with the other of saidrotatable enclosure and fourth rotatable means and characterized toeffect a predetermined mode of movement of the rotatable enclosurerelative to the first rotatable means;

(h) and coil spring means encircling the rotatable shaft means anddisposed to normally urge the rotatable enclosure away from the firstrotatable means.

24. The centrifugal clutch defined by claim 23, and further comprising aplurality of low friction bearing members disposed on the other of saidrotatable enclosure and fourth rotatable means for respective engagementby the cam surfaces of said plurality of flyweights.

25. The centrifugal clutch defined by claim 24, wherein the fourthrotatable means comprises a hub with a plurality of arms extendingradially outward therefrom, the outer end of each of said arms havingsaid flyweight or low friction bearing member mounted thereon.

26. The centrifugal clutch defined by claim 24, wherein the low frictionbearing members comprise rollers.

27. The centrifugal clutch defined by claim 23, wherein each of saidflyweights is replaceably mounted on said one of the rotatable enclosureand fourth rotatable means.

28. A centrifugal clutch, comprising:

(a) rotatable shaft means;

(b) first rotatable means mounted on the shaft means for rotationtherewith and axially stationary thereon, the first rotatable meanshaving a first clutching surface;

(c) second rotatable means mounted on the shaft means for rotationtherewith and defining a second clutching surface operable inassociation with the first clutching surface, the second rotatable meansincluding a bearing support portion engageable with the rotatable shaftmeans to permit axial movement thereover;

(d) third rotatable means mounted on the shaft means for rotationtherewith and including a bearing support portion engageable with therotatable shaft means to permit axial movement thereover;

(e) said second and third rotatable means being constructed and arrangedto cooperably merge and define a rigid rotatable enclosure with thebearing support portions axially spaced to provide distributed bearingsupport for the rigid enclosure as it moves axially over the rotatableshaft means;

(f) fourth rotatable means mounted on the shaft means for rotationtherewith and axially stationary thereon, the fourth rotation meansbeing disposed within the rotatable enclosure;

(g) a plurality of flyweights of pivotally mounted on one of therotatable enclosure and the fourth rotatable means and arranged to moveradially outward with increasing rotational velocity of the shaft means,each of said flyweights being engageable with the other of saidrotatable enclosure and the fourth rotable means to effect axialmovement of the rotatable enclosure relative to the first rotatablemeans;

(h) said second, third and fourth rotatable means being removable fromthe shaft means as a unit.

29. The centrifugal clutch defined by claim 28, and further comprisingcoil spring means encircling the rotatable shaft means and disposed tonormally urge the rotatable enclosure away from the first rotatablemeans.

30. The centrifugal clutch defined by claim 29, wherein the coil springmeans is constructed and arranged to be removed with the second, thirdand fourth rotatable means.

31. The centrifugal clutch defined by claim 28, wherein the fourthrotatable means is secured to the shaft means for rotation therewith;the rotatable enclosure is constructed for engagement by and rotationalmovement with the fourth rotatable means; and further comprisingremovable keeper means for maintaining the fourth rotational means insaid axially stationary position.

32. The centrifugal clutch defined by claim 31, wherein the keeper meanscomprises:

(a) abutment means disposed on the shaft means, the

fourth rotatable means being disposed in abutting engagement therewith;

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 3,574,366 4/1971 Thostenson 74-230.17 E 3,230,7871/1966 Siegal 74-230.17 E 2,317,339 4/1943 Steven 74-23().17 E

10 Harley 74230.17 E Brugghen et a1. 74-230.17 E Shaw 74230.17 E Heyer74230 17 E H111 74-230.17 E Thostenson 74230.17 CC Galleher 74230.17Nelson 74230.17 Larsson 74230.17

CHARLES J. MYHRE, Primary Examiner R. H. LAZARUS, Assistant Examiner

